Title HYDROCARBONS A-4.pdf ✅

CLASS : XIIth SUBJECT : CHEMISTRY DATE : DPP NO. : 4 2 (d) L.P.G. mainly contains butane and isobutane. 4 (a) CH2 = CH2 [O] 2HCOOH 5 (a) According to Markownikoff’s rule, the negative part of the reagent gets attached to that double bonded carbon atom which has least number of H-atoms. Thus, CH3 = CH ― CH3 HBr CH3 ―CH ― CH3 | Br 9 (b) Gasoline contains alkanes from C6 to C11 carbon atom. 10 (d) We know that, Al4C3 +12H2O→4Al(OH)3 +3CH4 Thus, in this reaction methane (CH4) is produced. 11 (d) Follow Saytzeff rule of elimination. 13 (b) Impurities of PH3 give garlic smell to C2H2. 14 (d) In the formation of an alkane from Grignard reagent, alkyl group always comes from Grignard reagent. Hence, the number of carbon atoms in the Grignard reagent and alkane formed Grignard reagent will be identical. So, the original alkyl halide is propyl bromide. 15 (c) Topic :-HYDROCARBONS CH CH [O] COOH COOH ; CH C CH3 H2O Hg 2+ /H2SO4 SOLUTION S
CH2 = C(OH)CH3⇌CH3COCH3; The mechanism involves tautomerism. 16 (d) C2H6 + 7 2 O2⟶2CO2 + 3H2O 17 (c) CH ≡ CH HBr CHBr = CH2 HBr CHBr2—CH3 KOH(alc.) CHBr = CH2 NaNH2 CH ≡ CH 18 (d) According to Markownikoff’s rule the addition of a reagent (HX) to an unsymmetrical alkene takes place in such a way that the negative part of the reagent will be attached to that carbon atom which contains lesser number of H-atom. Br | CH3 ―C = CH2 +HBr→CH3 ―C ― CH3 | | CH3 CH3 2-methylpropene 19 (b) Follow text. 20 (a) Br2solution is decolourized by alkene or alkyne or molecules having unsaturation.
ANSWER-KEY Q. 1 2 3 4 5 6 7 8 9 10 A. B D C A A C D A B D Q. 11 12 13 14 15 16 17 18 19 20 A. D B B D C D C D B A